Use Blender's bpy in projects outside Blender?
The easy way is to use blender. You can start it with cli options to run in the background (without gui) and to run a python script.

blender --background --python myscript.py


You can also start rendering from the cli without a script.

blender -b mymodel.blend --render-frame 1


or render an animation

blender -b mymodel.blend --frame-start 1 --frame-end 100 --render-anim


For something more interactive you can use blenders built-in python console

blender -b --python-console


The other option to get access to bpy without a normal blender install means you will need to compile your own copy of blender as a pymodule.